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Transgenesis and its use in animals |
Cahiers Agricultures. Volume 1, Number 5, 317-24, Novembre-Décembre 1992, Synthèse
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 Résumé
 Summary
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Author(s) : Louis-Marie Houdebine, Unité de différenciation cellulaire, INRA, 78352 Jouy-en-Josas Cedex, France.. |
Summary : Recent progress in genetic engineering and embryo manipulation allow the introduction of any DNA fragment into the genome of animals including farm animals. Direct microinjection of DNA solution into the pronuclei of embryo is the only techniques used in routine althrough its efficiency remains limited. The use of retroviral vectors is being studied namely for birds, in which embryo manipulation is not easily done. The use of embryonic stem cells (ES cells) appears very promising. These cells isolated from blastocystes can be cultured without being differenciated. They can be reintroduced into an embryo to generate chimeric animals. Foreign genes can be introduced into the cultured ES cells before they are transplanted into the embryo. Targeted gene transfer can also be achieved with ES cells leading to specific gene replacement. These techniques are being used only in mouse as long as ES cells have not been well characterized in other species. The availability of cow embryos to be used for DNA microinjection can be greatly increased when they are obtained from oocytes which were matured and fertilized in vitro. The same approach can be used for sheep and to some extent for goat and possibly for pig in the future. These new methods considerably facilitate gene studies. Some of these studies are about to become industrial projects. Proteins of pharmaceutical interest can be secreted in milk of laboratory and farm animals, and some of such proteins will be soon commercialized. Livestock animals will also take advantage of these techniques by becoming more resistant to diseases and by getting interesting genetic traits which cannot be provided by the conventional genetic selection. Transgenic laboratory animals and in some cases farm animals, start being used as very interesting biological models for the study of human diseases. Studies in progress aim at generating transgenic animals (pig, sheep) as possible source of organs for transplantation to human beings. It is generally admitted that transgenic animals will have a great impact on breeding in the 21st century. |
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